Boogie

I got few PM's asking for more info on a particular plane-vivat powered by a sm30 gas. I couldn't answer those questions myself, so I have sent a mail to the owner of this model- Piotr Urbanski. This is what he has written to me:

"Basic reason for being interested in gas for a pattern plane is of course the cost. Because my son is also involved in the hobby, we spend a lot of money on fuel, we have used about 250l (about 55 galons) of fuel (with 25% nitro) last year.
For the money we have spent on fuel, we could buy few gas engines. I also wanted to popularise the hobby.

It was very easy for me to get a gas pattern plane under 5kg. After weighing the powerplant (motor+exhaust+prop+motor mount+ignition) I realised that sm30 30 is just 400g(14 oz.) heavier than YS 1.40. The weight is so smalll beacuse, I have used my own, very light motor mount, pipes made by Stefan Gaudynski (100g-3,6oz for YS and 130g-4,6oz for sm30) and prop-wooden or carbon(about 70g-2,5oz lighter than APC).

My VIVAT with YS 1,40 (2003) weighs 4350g (9lbs 10 oz), so I knew that with gas it will be under 4800g (10lbs 10oz). Now I know that for converting pattern planes I have to choose models that weigh with YS 1.4 under 4400g (9lbs 12 oz), is quite wide at the cowl part (beacuse of 3 motor mounts used) and that have wings mounted using a pipe (carbon), because you have to move the wings forward in order to get the proper CG. Vivat is OK for this reasons, I only had to modify the front of the fuselage.
Here are my thoughts about flying:
Very powerful powerplant-it goes straightly up on 1/3 of the throttle!!!
Model is much faster than when using a Yamada, so I changed the prop from 17x12 to 18x10, and I also plan some changes to the motor, which maybe will decrease this huge amount of power, but will help in throttle managment -especially at low and medium RPM's.
Right know it is good to fly in the box with 150-170m (about 500 feet) on both sides) flying really big loops etc.

What is really great about gas is the incredible consumption of fuel- 0,35l (13 ounces) fuel tank gives me about 20 minutes of program flying!
After problems with tuning the engine, it starts by hand ( I haven't taken off the cowl for 30 flights.

If anyone is interested in buying a Vivat-which is really great for converting to gas look at www.modelairpol.com "

So that's it for now- if anyone is interested in any details just feel free to ask - I will try to answer them.

Boogie

I forgot to post photos. Here they are:

raptor5900

My Feedback: (4)

wow you have a vivat...i met the guys that sells them in the US. They are awsome.

Ryan Smith

My Feedback: (25)

Boogie,

What kind of plane is that in your avatar? I like it.

Boogie

Acroman330:
This is a photo of an Omega -a .90 pattern plane. You can get ne here (ARC) for $150. This particular model is covered with paper and oracover together. Powered by os 91FX.
Here is the bigger photo:

fdo300

My Feedback: (1)

Hi Boogie

I'm very interested on your friend engine setup on the Vivat, could you please ask him the next questions please:

How is the SM30 throttle transition compared to a OS 140 RX or YS ?? what kind of changes is planning to make to the engine to improve the transition ??

What RPM is he getting with the 18 x 10 prop ? prop brand ? idle RPM ??

Ask him for engine mount pictures, look like carbon fiber structure or not ?

Does the SM 30 produce more vibration than YS or OS engines ?

Best Regards

Fernando Viollier

Boogie

1)You can compare it to OS.- The power increases quite fast after about 40% pf throttle applied.

2) He wants to decrease the hole in the carb to get better transition (but decrease power) and also lenghten fuel inlet line (to the carb).

3) He uses MENZ props. With 18x10 ULTRA he has 7700RPMs, on 18x10S (wide blade)-7500, on 17x12S(also wide blade)-7650.
Idle RPMs -2000

4) The motor mount is in fact 3 motor mounts in one, made out of carbon & balsa all covered with anti-vibration rubber.

5)Unexpectably, but ir produces less vibration than his YS!!! It is because of the motor mount and the motor is better balanced

PlaneKrazee

My Feedback: (14)

Has anyone else used this engine?